Digitally stored electronic maps are used to provide directions to users of mobile devices, for example, using any of a wide array of standalone map or direction application programs or apps. Today's electronic maps correctly determine where a mobile device is within a few feet or meters, or show where the user of that mobile device is on the electronic map in real time. Electronic maps also typically include other functionality, such as providing turn-by-turn directions to nearly any location. Additional elements such as traffic or wrecks may also be shown.
Electronic maps also appear in other applications aside from standalone mapping applications. For example, ride sharing applications, taxi applications, video games, and other applications may use digital maps. These or other applications can obtain electronic maps by calling a map server computer through an Application Programming Interface (API). Thus, a single electronic map provider that owns or operates the server computer may supply the electronic maps for many different applications.
When a mobile device is using an electronic map, the location of the mobile device can be determined using WiFi or the Global Positioning System (GPS), which reports a device location using latitude and longitude, and optionally height and time as well. This location data, as well as other data, may be collected by the electronic map provider and may be termed “telemetry” data for the mobile device. Other information, such as speed, heading, acceleration, and deceleration may be calculated using the GPS data. Individually, or in combination, the telemetry data may be used for many different applications. For example, speed may be used to estimate the average or expected speed of travel on a road. The average or expected speed of travel may then be used, along with other information, to accurately estimate arrival time at a destination. However, managing the large amounts of telemetry data that can be received is challenging. In fact, there may be so many speed observations for a road that storing the speed observations, or determining a speed estimation, may become an extremely time and resource intensive process.